1. Field of the Invention
The present invention relates to an apparatus for cleaning the interior of tubes used in heat exchanger bundles. More particularly, the present invention relates to an apparatus for simultaneously cleaning the interior of several tubes within a heat exchanger bundle on site.
2. Description of the Related Art
Heat exchangers are used for the transfer of heat from one fluid medium to another. One of the fluids passes through a series of conduits, or tubes, while the other passes on the outside of the tubes. During this process, carbonaceous and calcareous deposits form on the interior of the individual tubes. Debris and other dirt collects on the surface of the individual tubes. To maintain efficient operation, it is necessary to periodically remove the tubes and clean their interior and exterior surfaces.
One method of cleaning the interior of heat exchanger tubes includes the progressive insertion of a small diameter tube, known as a lance, into the heat exchanger tube and the pumping of high pressure water through the lance to clean the interior of the tube. The water pressure in a lance may easily exceed 10,000 psi with flow rates in excess of 100 gallons per minute. Prior art devices call for the lance to be manually operated, including the manual advancing of the lance into the exchanger tube. It will be appreciated that the manual operation of a lance is unsatisfactory for a number of reasons. First, the operator is required to overcome the force of the water pressure when inserting the lance into the tube. Further, should the lance wall rupture, the operator or a bystander may be injured by the high pressure water flow. An operator may also be injured as a result of back-splash from the lance during the insertion of the lance in the tube. Furthermore, the manual operation of a lance is time consuming and costly since only one lance may be used in manual operations.
Various mechanical devices have been used in an effort to overcome the above deficiencies in cleaning the interior of heat exchanger tubes. U.S. Pat. No. 3,903,912 to Ice et al. discloses a multiple lance cleaning system which includes lance positioning and drive means and which uses exposed lance tubes. The use of exposed lance tubes poses a danger to an operator in the event of a lance wall rupture.
U.S. Pat. No. 3,817,262 to Cradeur discloses a multiple lance cleaning system having a lance positioner and drive system and also uses exposed lance tubes. As in the Ice disclosure, the operator is exposed to the danger of potential lance tube rupture.
U.S. Pat. No. 3,901,252 to Riebe discloses a multiple lance system including a lance drive and enclosed lance tubes, manifold and water lines. Unlike the Ice and Cradeur lances, the lance disclosed in Riebe is enclosed. However, the Riebe apparatus features another problem in that the water inlet line is pulled in and out of the lance enclosure during operations. Such a configuration causes wear and tear on the water hose which could lead to its failure under high pressure. Furthermore, at various points in the operation, the section of the water hose subject to wear and tear can be found at least partly protruding outside the lance enclosure in a location wherein a rupture of the hose could endanger the operator.
U.S. Pat. No. 4,856,545 to Krajicek discloses a multi-lance tube cleaning system having a lance drive means, lance tubes and manifold, and multiple high pressure water lines within an enclosed structure. Unlike the apparatus taught in Riebe, the hose is not dragged in and out of the enclosure so that wear and tear on the hose is minimized. Rather, the water hose is deployed within its own protective enclosure which is located immediately below the lance enclosure. The hose is permanently attached to its protective enclosure at its point of entry. This tends to minimize the wear and tear on the hose. The protective hose enclosure serves to protect personnel in the event of a water hose rupture. However, as can be appreciated from the disclosure of the Krajicek patent, for example in FIG. 8 of that reference, the water hose leaves its own protective enclosure and enters the lance enclosure by way of a long slot which connects the two enclosures. The presence of the slot is problematical in that it makes it possible for one or more of the lances to bend and enter the slot. This allows bending of the lance which may cause it to malfunction. In addition, the lance entering the slot can contact the water hose located below the slot and cause the water hose to rupture.
Accordingly, there exists a need for an improved tube bundle cleaner having means for transporting water to the lances, means for accurately supporting and positioning the lances during operation, means for retracting the water pressure line in an efficient and thorough manner, and which also has enclosed tube lances and enclosed water hose which will prevent the lances from bending out of shape and from contacting and possibly damaging the water hose.
While there are other disclosures directed to the cleaning of the interior of heat exchanger bundles (such as U.S. Pat. Nos. 3,589,388; 2,494,380; 1,694,371; and 620,224), none discloses or suggests a multi-lance cleaning system having enclosed lances and enclosed hose wherein the lances are prevented from bending so much as to leave their enclosure and possibly enter the water hose enclosure.